* [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap
@ 2020-07-10 19:40 Uladzislau Rezki (Sony)
2020-07-10 19:44 ` Uladzislau Rezki
2020-07-10 19:44 ` Matthew Wilcox
0 siblings, 2 replies; 7+ messages in thread
From: Uladzislau Rezki (Sony) @ 2020-07-10 19:40 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, LKML, Uladzislau Rezki, Hillf Danton, Michal Hocko,
Matthew Wilcox, Oleksiy Avramchenko, Steven Rostedt
Before triggering a BUG() it would be useful to understand
how two areas overlap between each other. Print information
about start/end addresses of both VAs and their addresses.
For example if both are identical it could mean double free.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
mm/vmalloc.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 5a2b55c8dd9a..1679b01febcd 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va,
else if (va->va_end > tmp_va->va_start &&
va->va_start >= tmp_va->va_end)
link = &(*link)->rb_right;
- else
+ else {
+ pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
+ va, va->va_start, va->va_end, tmp_va,
+ tmp_va->va_start, tmp_va->va_end);
+
BUG();
+ }
} while (*link);
*parent = &tmp_va->rb_node;
@@ -1993,6 +1998,9 @@ static void vmap_init_free_space(void)
insert_vmap_area_augment(free, NULL,
&free_vmap_area_root,
&free_vmap_area_list);
+ insert_vmap_area_augment(free, NULL,
+ &free_vmap_area_root,
+ &free_vmap_area_list);
}
}
}
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap
2020-07-10 19:40 [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap Uladzislau Rezki (Sony)
@ 2020-07-10 19:44 ` Uladzislau Rezki
2020-07-10 19:44 ` Matthew Wilcox
1 sibling, 0 replies; 7+ messages in thread
From: Uladzislau Rezki @ 2020-07-10 19:44 UTC (permalink / raw)
To: Andrew Morton
Cc: Andrew Morton, linux-mm, LKML, Hillf Danton, Michal Hocko,
Matthew Wilcox, Oleksiy Avramchenko, Steven Rostedt
> Before triggering a BUG() it would be useful to understand
> how two areas overlap between each other. Print information
> about start/end addresses of both VAs and their addresses.
>
> For example if both are identical it could mean double free.
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
> mm/vmalloc.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 5a2b55c8dd9a..1679b01febcd 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va,
> else if (va->va_end > tmp_va->va_start &&
> va->va_start >= tmp_va->va_end)
> link = &(*link)->rb_right;
> - else
> + else {
> + pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
> + va, va->va_start, va->va_end, tmp_va,
> + tmp_va->va_start, tmp_va->va_end);
> +
> BUG();
> + }
> } while (*link);
>
> *parent = &tmp_va->rb_node;
> @@ -1993,6 +1998,9 @@ static void vmap_init_free_space(void)
> insert_vmap_area_augment(free, NULL,
> &free_vmap_area_root,
> &free_vmap_area_list);
> + insert_vmap_area_augment(free, NULL,
> + &free_vmap_area_root,
> + &free_vmap_area_list);
> }
> }
> }
>
Please ignore this patch, i will upload v2.
Sorry for inconvenience.
--
Vlad Rezki
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap
2020-07-10 19:40 [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap Uladzislau Rezki (Sony)
2020-07-10 19:44 ` Uladzislau Rezki
@ 2020-07-10 19:44 ` Matthew Wilcox
2020-07-10 19:45 ` Uladzislau Rezki
2020-07-10 20:00 ` Uladzislau Rezki
1 sibling, 2 replies; 7+ messages in thread
From: Matthew Wilcox @ 2020-07-10 19:44 UTC (permalink / raw)
To: Uladzislau Rezki (Sony)
Cc: Andrew Morton, linux-mm, LKML, Hillf Danton, Michal Hocko,
Oleksiy Avramchenko, Steven Rostedt
On Fri, Jul 10, 2020 at 09:40:42PM +0200, Uladzislau Rezki (Sony) wrote:
> Before triggering a BUG() it would be useful to understand
> how two areas overlap between each other. Print information
> about start/end addresses of both VAs and their addresses.
>
> For example if both are identical it could mean double free.
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
> mm/vmalloc.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 5a2b55c8dd9a..1679b01febcd 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va,
> else if (va->va_end > tmp_va->va_start &&
> va->va_start >= tmp_va->va_end)
> link = &(*link)->rb_right;
> - else
> + else {
> + pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
> + va, va->va_start, va->va_end, tmp_va,
> + tmp_va->va_start, tmp_va->va_end);
It might be helpful to have a "vmalloc:" prefix to that string to indicate
where to start searching. And I don't think we're supposed to use %px
without a really good justification these days.
Can we do without the BUG()? Maybe just break out and decline to insert
the conflicting range?
> BUG();
> + }
> } while (*link);
>
> *parent = &tmp_va->rb_node;
> @@ -1993,6 +1998,9 @@ static void vmap_init_free_space(void)
> insert_vmap_area_augment(free, NULL,
> &free_vmap_area_root,
> &free_vmap_area_list);
> + insert_vmap_area_augment(free, NULL,
> + &free_vmap_area_root,
> + &free_vmap_area_list);
This is surely testing code that you forgot to delete?
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap
2020-07-10 19:44 ` Matthew Wilcox
@ 2020-07-10 19:45 ` Uladzislau Rezki
2020-07-10 20:00 ` Uladzislau Rezki
1 sibling, 0 replies; 7+ messages in thread
From: Uladzislau Rezki @ 2020-07-10 19:45 UTC (permalink / raw)
To: Matthew Wilcox
Cc: Uladzislau Rezki (Sony),
Andrew Morton, linux-mm, LKML, Hillf Danton, Michal Hocko,
Oleksiy Avramchenko, Steven Rostedt
On Fri, Jul 10, 2020 at 08:44:06PM +0100, Matthew Wilcox wrote:
> On Fri, Jul 10, 2020 at 09:40:42PM +0200, Uladzislau Rezki (Sony) wrote:
> > Before triggering a BUG() it would be useful to understand
> > how two areas overlap between each other. Print information
> > about start/end addresses of both VAs and their addresses.
> >
> > For example if both are identical it could mean double free.
> >
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > ---
> > mm/vmalloc.c | 10 +++++++++-
> > 1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 5a2b55c8dd9a..1679b01febcd 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va,
> > else if (va->va_end > tmp_va->va_start &&
> > va->va_start >= tmp_va->va_end)
> > link = &(*link)->rb_right;
> > - else
> > + else {
> > + pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
> > + va, va->va_start, va->va_end, tmp_va,
> > + tmp_va->va_start, tmp_va->va_end);
>
> It might be helpful to have a "vmalloc:" prefix to that string to indicate
> where to start searching. And I don't think we're supposed to use %px
> without a really good justification these days.
>
> Can we do without the BUG()? Maybe just break out and decline to insert
> the conflicting range?
>
> > BUG();
> > + }
> > } while (*link);
> >
> > *parent = &tmp_va->rb_node;
> > @@ -1993,6 +1998,9 @@ static void vmap_init_free_space(void)
> > insert_vmap_area_augment(free, NULL,
> > &free_vmap_area_root,
> > &free_vmap_area_list);
> > + insert_vmap_area_augment(free, NULL,
> > + &free_vmap_area_root,
> > + &free_vmap_area_list);
>
> This is surely testing code that you forgot to delete?
Matthew, you are super fast!!! :)
--
Vlad Rezki
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap
2020-07-10 19:44 ` Matthew Wilcox
2020-07-10 19:45 ` Uladzislau Rezki
@ 2020-07-10 20:00 ` Uladzislau Rezki
2020-07-10 20:01 ` Matthew Wilcox
1 sibling, 1 reply; 7+ messages in thread
From: Uladzislau Rezki @ 2020-07-10 20:00 UTC (permalink / raw)
To: Matthew Wilcox
Cc: Uladzislau Rezki (Sony),
Andrew Morton, linux-mm, LKML, Hillf Danton, Michal Hocko,
Oleksiy Avramchenko, Steven Rostedt
On Fri, Jul 10, 2020 at 08:44:06PM +0100, Matthew Wilcox wrote:
> On Fri, Jul 10, 2020 at 09:40:42PM +0200, Uladzislau Rezki (Sony) wrote:
> > Before triggering a BUG() it would be useful to understand
> > how two areas overlap between each other. Print information
> > about start/end addresses of both VAs and their addresses.
> >
> > For example if both are identical it could mean double free.
> >
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > ---
> > mm/vmalloc.c | 10 +++++++++-
> > 1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 5a2b55c8dd9a..1679b01febcd 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va,
> > else if (va->va_end > tmp_va->va_start &&
> > va->va_start >= tmp_va->va_end)
> > link = &(*link)->rb_right;
> > - else
> > + else {
> > + pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
> > + va, va->va_start, va->va_end, tmp_va,
> > + tmp_va->va_start, tmp_va->va_end);
>
> It might be helpful to have a "vmalloc:" prefix to that string to indicate
> where to start searching. And I don't think we're supposed to use %px
> without a really good justification these days.
>
That makes sense, i will add such prefix for sure. As for %px i can just
use a casting to (unsigned long) and 0x%lx prefix.
>
> Can we do without the BUG()? Maybe just break out and decline to insert
> the conflicting range?
>
When i developed that logic, i was thinking about that but for some
reason i went with BUG_ON(), do not remember why. But i agree we shold
avoid of it. Let me think about it one more time.
> > BUG();
> > + }
> > } while (*link);
> >
> > *parent = &tmp_va->rb_node;
> > @@ -1993,6 +1998,9 @@ static void vmap_init_free_space(void)
> > insert_vmap_area_augment(free, NULL,
> > &free_vmap_area_root,
> > &free_vmap_area_list);
> > + insert_vmap_area_augment(free, NULL,
> > + &free_vmap_area_root,
> > + &free_vmap_area_list);
>
> This is surely testing code that you forgot to delete?
>
Yes, i forgot to remove it.
Thanks for your comments!
--
Vlad Rezki
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap
2020-07-10 20:00 ` Uladzislau Rezki
@ 2020-07-10 20:01 ` Matthew Wilcox
2020-07-10 20:04 ` Uladzislau Rezki
0 siblings, 1 reply; 7+ messages in thread
From: Matthew Wilcox @ 2020-07-10 20:01 UTC (permalink / raw)
To: Uladzislau Rezki
Cc: Andrew Morton, linux-mm, LKML, Hillf Danton, Michal Hocko,
Oleksiy Avramchenko, Steven Rostedt
On Fri, Jul 10, 2020 at 10:00:30PM +0200, Uladzislau Rezki wrote:
> On Fri, Jul 10, 2020 at 08:44:06PM +0100, Matthew Wilcox wrote:
> > On Fri, Jul 10, 2020 at 09:40:42PM +0200, Uladzislau Rezki (Sony) wrote:
> > > Before triggering a BUG() it would be useful to understand
> > > how two areas overlap between each other. Print information
> > > about start/end addresses of both VAs and their addresses.
> > >
> > > For example if both are identical it could mean double free.
> > >
> > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > > ---
> > > mm/vmalloc.c | 10 +++++++++-
> > > 1 file changed, 9 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > > index 5a2b55c8dd9a..1679b01febcd 100644
> > > --- a/mm/vmalloc.c
> > > +++ b/mm/vmalloc.c
> > > @@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va,
> > > else if (va->va_end > tmp_va->va_start &&
> > > va->va_start >= tmp_va->va_end)
> > > link = &(*link)->rb_right;
> > > - else
> > > + else {
> > > + pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
> > > + va, va->va_start, va->va_end, tmp_va,
> > > + tmp_va->va_start, tmp_va->va_end);
> >
> > It might be helpful to have a "vmalloc:" prefix to that string to indicate
> > where to start searching. And I don't think we're supposed to use %px
> > without a really good justification these days.
> >
> That makes sense, i will add such prefix for sure. As for %px i can just
> use a casting to (unsigned long) and 0x%lx prefix.
That's not the point. Linus wants us to not display actual pointers to
the user.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap
2020-07-10 20:01 ` Matthew Wilcox
@ 2020-07-10 20:04 ` Uladzislau Rezki
0 siblings, 0 replies; 7+ messages in thread
From: Uladzislau Rezki @ 2020-07-10 20:04 UTC (permalink / raw)
To: Matthew Wilcox
Cc: Uladzislau Rezki, Andrew Morton, linux-mm, LKML, Hillf Danton,
Michal Hocko, Oleksiy Avramchenko, Steven Rostedt
On Fri, Jul 10, 2020 at 09:01:38PM +0100, Matthew Wilcox wrote:
> On Fri, Jul 10, 2020 at 10:00:30PM +0200, Uladzislau Rezki wrote:
> > On Fri, Jul 10, 2020 at 08:44:06PM +0100, Matthew Wilcox wrote:
> > > On Fri, Jul 10, 2020 at 09:40:42PM +0200, Uladzislau Rezki (Sony) wrote:
> > > > Before triggering a BUG() it would be useful to understand
> > > > how two areas overlap between each other. Print information
> > > > about start/end addresses of both VAs and their addresses.
> > > >
> > > > For example if both are identical it could mean double free.
> > > >
> > > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > > > ---
> > > > mm/vmalloc.c | 10 +++++++++-
> > > > 1 file changed, 9 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > > > index 5a2b55c8dd9a..1679b01febcd 100644
> > > > --- a/mm/vmalloc.c
> > > > +++ b/mm/vmalloc.c
> > > > @@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va,
> > > > else if (va->va_end > tmp_va->va_start &&
> > > > va->va_start >= tmp_va->va_end)
> > > > link = &(*link)->rb_right;
> > > > - else
> > > > + else {
> > > > + pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
> > > > + va, va->va_start, va->va_end, tmp_va,
> > > > + tmp_va->va_start, tmp_va->va_end);
> > >
> > > It might be helpful to have a "vmalloc:" prefix to that string to indicate
> > > where to start searching. And I don't think we're supposed to use %px
> > > without a really good justification these days.
> > >
> > That makes sense, i will add such prefix for sure. As for %px i can just
> > use a casting to (unsigned long) and 0x%lx prefix.
>
> That's not the point. Linus wants us to not display actual pointers to
> the user.
>
Ahh, Got it!
Then i will just remove information about addresses of two VAs.
Hope that will work.
--
Vlad Rezki
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-07-10 20:04 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2020-07-10 19:40 [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap Uladzislau Rezki (Sony)
2020-07-10 19:44 ` Uladzislau Rezki
2020-07-10 19:44 ` Matthew Wilcox
2020-07-10 19:45 ` Uladzislau Rezki
2020-07-10 20:00 ` Uladzislau Rezki
2020-07-10 20:01 ` Matthew Wilcox
2020-07-10 20:04 ` Uladzislau Rezki
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